Project title: Proteomic signatures of an early life asthma-protective exposure Challenge Area: 03 Biomarker discovery and validation Challenge Topic: Validation of new exposure assessment methodologies (03-ES-101) Project Summary Mounting evidence suggests that environmental exposures, particularly when occurring at a critical developmental window in early life, can profoundly affect the phenotypes associated with complex diseases such as allergic asthma. In particular, several longitudinal population studies have consistently shown that early life and possibly even prenatal exposure to certain domestic animals (e.g., indoor dogs) is associated with strong protection against asthma and asthma-related phenotypes (allergy, eczema) later in life. The challenge at this stage is to elucidate the biological mechanisms responsible for the protective effects of dog exposure as a step towards leveraging these mechanisms for preventive purposes. The overall goal of this Project therefore is to begin identifying these mechanisms using new mass spectrometry-based methodologies. Our specific aim is to identify and characterize proteomic signatures of early life dog exposure in the plasma or serum of children who have or have not been exposed to dogs in early life, and who were or were not diagnosed with asthma by age 5-8 yrs. The hypotheses we seek to test are: a) specific signatures of early dog exposure are detectable in the proteome of the exposed children;b) these signatures mark molecules targeted by environmental signals and are related to disease pathogenesis, and c) a comparison of signatures by exposure and disease status provide clues for the identification of molecular pathways activated by environmental cues and which are involved in conferring protection from asthma. In order to achieve our goals, we will rely on our synergistic expertise in proteomics (Lau), epidemiology (Halonen), allergy biology and immunology (Vercelli), and biostatistics (Billheimer) as well as on a unique set of samples and data from the Infant Immune Study (IIS). This longitudinal study of asthma and allergy, conducted at the Arizona Respiratory Center, University of Arizona, enrolled at birth a large population of healthy children and is still following them 8 years later, gathering detailed phenotypic information about immunological parameters, allergic sensitization and lung function. Relevant to the current application, a bank has been created that houses plasma and/or serum samples obtained from IIS children at multiple time points. This wealth of samples and information will allow us to establish robust correlations between the biomarkers identified through the proposed experimental plan and environmental exposure and/or the disease outcome of asthma. Recent developments in mass spectrometry (MS) ionization methods and instrumentation now make possible the rapid, high throughput analysis of proteins and site-specific identification of post-translational modifications. MS is the method of choice for sequencing peptides and proteins with limited amounts of available sample, targeting low abundance proteins and detecting low rates of important modifications. These analytical capabilities will drive the future growth of biomarker discovery, validation, and implementation. The University of Arizona (UA) will leverage world-class competencies in proteomics and biostatistics for biomarker discovery and development. In particular, a collaborative effort of basic and clinical scientists was initiated in 2008 focusing on the development of serum biomarkers using a small set of samples from a well-defined cohort of human samples, with which we will explore the effect of pre-birth exposure of allergens in asthma development. The potential impact of our project is both broad and significant. Asthma imposes a heavy burden on society because it currently affects 10-15% of the population in many western nations, including the United States, and it is the most common chronic disease in childhood. Our results will shed light on the pathways harnessed by a common environmental exposure to modify susceptibility to this prototypic complex disease. Moreover, the development of novel approaches to the discovery of biomarkers related to protective environmental exposures would be readily applicable to multiple other conditions in which phenotypic outcomes are determined by interactions between environmental and endogenous factors. The strategies developed through our project may therefore help in translating protective exposures into effective preventive and/or therapeutic strategies. A key component is that the proposed longitudinal design will allow for the examination not only of plasma samples from multiple individuals, but also of samples obtained at different times from the same individuals. Our study is therefore likely to provide novel insights into the proteome's stability over time, and the extent to which intra- and inter-individual in vivo variations both exist. Public Health Relevance: Asthma continues to be a major health problem in the United States and worldwide. Asthma affects the health and quality of life of millions of children and adults. It has been suggested that exposure to microbial products in early life may have both systemic (decreased aeroallergen sensitization) and local (decreased airway inflammation) effects that may protect against the development of asthma. The goal of this Project is to initiate a dissection of these mechanisms by new mass spectrometry-based methodologies to identify and characterize proteomic signatures of early life dog exposure in the plasma of children who have or have not been exposed to dogs in early life, and who were, or were not, diagnosed with asthma by age 5-8 yrs.